This invention relates to a process for the preparation of pyrogallol. In a particular aspect, it relates to a process for the preparation of pyrogallol from glutaric ester and dialkoxymalonic ester.
Pyrogallol has many important uses, e.g. in photographic developers, as a mordant for wool, and in staining of leather. It is usually prepared from gallic acid by heating as described by Rinderknecht and Niemann, J. Am. Chem. Soc. 70, 2605 (1948), although Stevens in U.S. Pat. No. 2,603,662 disclosed a process involving chlorination of p-tert. butylphenol and hydrolysis of the product. Gallic acid is made principally by saponification of natural product tannic acids which are chiefly obtained from nutgalls gathered in Turkey and from Tara powder obtained from a plant species found at high altitudes in the Peruvian Andes. A method of synthesis has been disclosed by C. D. Hurd, U.S. Pat. No. 3,560,569. Nevertheless, gallic acid and pyrogallol are high-priced commodities which undoubtedly have been kept from many markets where they would be widely used at a lower price.